1. Field of the Invention
The present invention relates to solid state lasers. More specifically, the present invention relates to solid state lasers operative in the 8-12 micron range.
2. Description of the Related Art
Lasers are currently widely used for communication, research and development, manufacturing, directed energy and numerous other applications. For many applications, the energy efficiency, power and lightweight of solid state lasers makes these devices particularly useful. Solid state lasers currently lase in the range of one to three microns.
For certain applications, there is a need to reach longer laser operating wavelengths. In particular, there is interest in the 8-12 micron (xcexcm) region.
Several groups have demonstrated wavelength conversion to this region using various solid-state lasers, or the output from optical parametric oscillators (OPOs) as pump sources for longer wavelength OPOs and difference frequency generation crystals. See for example: 1) S. Chandra, T. H. Allik, G. Catella, R. Utano, J. A. Hutchinson, xe2x80x9cContinuously tunable 6-14 xcexcm silver gallium selenide optical parametric oscillator pumped at 1.57 xcexcm,xe2x80x9d Appl. Phys. Lett. 71, 584-586 (1997); 2)T. Allik, S. Chandra, D. M. Rines, P. G. Schunemann, J. A. Hutchinson, and R. Utano, xe2x80x9c7-12 xcexcm generation using a Cr, Er:YSGG pump laser and CdSe and ZnGeP2 OPOs,xe2x80x9d in Advanced Solid State Lasers. OSA Trends in Optics and Photonics (Optical Society of America, Washington. D. C., 1997), Vol. 10, pp. 265-266; and 3) R. Utano and M. J. Ferry, xe2x80x9c8-12 xcexcm generation using difference frequency generation in AgGaSe2 of a Nd:YAG pumped KTP OPO,xe2x80x9d in Advanced Solid State Lasers, OSA Trends in Optics and Photonics (Optical Society of America, Washington, D.C., 1997), Vol. 10, pp. 267-269[WJB1].
One approach involved the use of a flashlamp pumped Cr, Er:YSGG laser emitting at 2.79 microns to pump a cadmium selenide (CdSe) OPO. This approach has been represented as being effective to yield a tunable 8-12 micron output. Unfortunately, the poor overall electrical efficiency of the Cr, Er:YSGG pump laser, together with its fairly long (50 ns) output pulse width, result in a less than optimal CdSe OPO pump source.
Hence, a need remains in the art for an efficient, tunable system or method for converting the output of a typical 1-3 xcexcm laser to the 8-12 xcexcm range.
The need in the art is addressed by the solid state laser of the present invention. The inventive laser includes a pump laser for providing an input beam. An optical parametric oscillator (OPO) provides a first stage which shifts the input beam from the first wavelength to a second wavelength. In accordance with the present teachings, a second stage mechanism is included for shifting the beam from a second wavelength to a third wavelength.
In the illustrative embodiment, the mechanism for shifting the beam from the second wavelength to the third wavelength is an OPO using a cadmium selenide crystal. In the illustrative embodiment, the input beam is a one-micron beam and the third wavelength is in the range of 8-12 microns. In the best mode, the first stage OPO includes a crystal which is x-cut potassium titanyl arsenate. A tuning mechanism with an associated controller is provided to tune the OPO as required for a particular application.
The invention provides a novel and efficient system and method for providing an output beam of collimated energy in the 8-12 micron range.